Because of Gravity, Basically a force so strong it constantly pulls us to the earth with 1 G (Maybe 100 pounds of force constantly pulling us to the earth)
This being a perfect collision means no energy is lost during the collision. Because this question asks for speed and not velocity, the speed will be the same because the final energy is the same. The speed after the collision would therefore be 1.27 m/s.
Explanation:
Given that, you are taking a picture of a giraffe that is standing far away from you. The image is just too small, so you swap the 60-mm-focal-length lens in your camera for a 960 mm telephoto lens such that,


We need to find the the factor with which the size of the image increases. It can be calculated by taking ratios of both 
So, 

So, the size of image increases by a factor of 16. Hence, this is the required solution.